Older ladder systems oriented within narrow aisles in some stores and warehouses were too wide and consumed too much of the width of the aisle. Employees of such stores and warehouses had difficulty passing the ladder, particularly when they were carrying packages or some other object. In one region, a local code even forbade the use of a dual track ladder of this type.
More recent ladder systems have been redesigned to include a feature that will permit it to fold out of the way against a rack or storage shelf when not in use. With this feature, the ladder system occupies a much smaller portion of the aisle width. As a result, employees of stores and warehouses using these ladder systems can pass by the ladder system in the aisle without difficulty.
An example of a more recent ladder system is shown in FIG. 1, which has been reproduced from U.S. Pat. No. 6,619,427 to Kerr (hereafter “Kerr”). In Kerr, a ladder 20 is positioned between storage shelves 22, 24 defining an aisle 26. The ladder 20 is slidably attached to a first lateral rod 28 of an overhead roller structure 30, meaning the ladder 20 can translate along the first lateral rod 28. The overhead roller structure 30 also includes a second lateral rod 32 in some embodiments, with the first and second lateral rods 28, 32 connected to and extending between first and second longitudinal members 34, 36. The first and second longitudinal members 34, 36 are slidably attached to an overhead guide track 38 extending along the storage shelves 22, 24. Thus, the ladder 20 can also move longitudinally along the aisle 26 because the overhead roller structure 30 can translate longitudinally along the overhead guide track 38.
Kerr also teaches that the ladder 20 can fold mostly out of the way of the aisle 26 due to a pivot 40 and a latch 42. When the ladder 20 is not in use, an employee can disengage the latch 42 and rotate the ladder 20 about the pivot 40. Once rotated, the ladder 20 is positioned substantially against the storage shelf 22, making the aisle 26 much more passable.
Yet even recent ladder systems have room for improvement in some environments. Many existing ladder systems have very large overhead roller structures with two lateral rods. For one, large roller structures can be difficult to ship or store when not in use, especially where the roller structures are welded together. Also, a large roller structure inhibits the ladder from traveling to ends of the aisles. The roller structures are long to accommodate at least two lateral rods. The guide tracks mounted on the shelves, moreover, do not extend beyond the ends of the shelves. Therefore, even though distal ends of the roller structure may travel to the ends of the aisles, the ladder cannot travel to the ends of the aisles since the ladder is generally centered along a length of the roller structure. Objects on shelves that are elevated and stored towards the end of the aisles can be difficult to access.
Still further, many existing ladder systems are unnecessarily complex, particularly at the attachment point(s) between the overhead roller structure and the ladder. Many stores, libraries, warehouses, and the like do not have aisles that require ladders to move laterally in an aisle between the shelves. Many existing ladder systems include additional roller structures for this purpose, however. While this capability may be advantageous in warehouses (1) with wide aisles that (2) require employees to move quickly from one shelf to an opposing shelf in the same aisle, this additional roller structure is overkill for many if not most stores, libraries, warehouses, and the like.
Thus, there is a long-felt need for a ladder system that has a compact overhead roller structure and that is not unnecessarily complex.